﻿// Copyright 2009-2024 Josh Close
// This file is a part of CsvHelper and is dual licensed under MS-PL and Apache 2.0.
// See LICENSE.txt for details or visit http://www.opensource.org/licenses/ms-pl.html for MS-PL and http://opensource.org/licenses/Apache-2.0 for Apache 2.0.
// https://github.com/JoshClose/CsvHelper
using CsvHelper.Configuration;
using CsvHelper.TypeConversion;
using System.Linq.Expressions;

namespace CsvHelper.Expressions;

/// <summary>
/// Creates primitive records.
/// </summary>
public class PrimitiveRecordCreator : RecordCreator
{
	/// <summary>
	/// Initializes a new instance using the given reader.
	/// </summary>
	/// <param name="reader">The reader.</param>
	public PrimitiveRecordCreator(CsvReader reader) : base(reader) { }

	/// <summary>
	/// Creates a <see cref="Delegate"/> of type <see cref="Func{T}"/>
	/// that will create a record of the given type using the current
	/// reader row.
	/// </summary>
	/// <param name="recordType">The record type.</param>
	protected override Delegate CreateCreateRecordDelegate(Type recordType)
	{
		var method = typeof(IReaderRow).GetProperty("Item", typeof(string), new[] { typeof(int) })!.GetGetMethod()!;
		Expression fieldExpression = Expression.Call(Expression.Constant(Reader), method, Expression.Constant(0, typeof(int)));

		var memberMapData = new MemberMapData(null)
		{
			Index = 0,
			TypeConverter = Reader.Context.TypeConverterCache.GetConverter(recordType)
		};
		memberMapData.TypeConverterOptions = TypeConverterOptions.Merge(new TypeConverterOptions { CultureInfo = Reader.Configuration.CultureInfo }, Reader.Context.TypeConverterOptionsCache.GetOptions(recordType));

		fieldExpression = Expression.Call(Expression.Constant(memberMapData.TypeConverter), "ConvertFromString", null, fieldExpression, Expression.Constant(Reader), Expression.Constant(memberMapData));
		fieldExpression = Expression.Convert(fieldExpression, recordType);

		var funcType = typeof(Func<>).MakeGenericType(recordType);

		return Expression.Lambda(funcType, fieldExpression).Compile();
	}
}
